High-k and p-type work function metal first fabrication process having improved annealing process flows

ABSTRACT

Embodiments are directed to a method of forming portions of a fin-type field effect transistor (FinFET). The method includes forming at least one fin, and forming a dielectric layer over at least a portion of the at least one fin. The method further includes forming a work function layer over at least a portion of the dielectric layer. The method further includes forming a source region or a drain region adjacent the at least one fin, and performing an anneal operation, wherein the anneal operation anneals the dielectric layer and either the source region or the drain region, and wherein the work function layer provides a protection function to the at least a portion of the dielectric layer during the anneal operation.

BACKGROUND

The present disclosure relates in general to semiconductor devicestructures and their fabrication. More specifically, the presentdisclosure relates to the fabrication of a fin-type field effecttransistor (FinFET) using a high-k and p-type work function metal firstfabrication process that improves, inter alia, source/drain activationannealing and dielectric reliability annealing.

Typical semiconductor devices are formed using active regions of awafer. The active regions are defined by isolation regions used toseparate and electrically isolate adjacent semiconductor devices. Forexample, in an integrated circuit having a plurality of metal oxidesemiconductor field effect transistors (MOSFETs), each MOSFET has asource and a drain that are formed in an active region of asemiconductor layer by implanting n-type or p-type impurities in thelayer of semiconductor material. Disposed between the source and thedrain is a channel (or body) region. Disposed above the body region is agate electrode. The gate electrode and the body are spaced apart by agate dielectric layer.

One particularly advantageous type of MOSFET is known generally as afin-type field effect transistor (FinFET). FIG. 1A depicts athree-dimensional view of an exemplary FinFET 100, which includes ashallow trench isolation (STI) region 104 for isolation of active areasfrom one another. The basic electrical layout and mode of operation ofFinFET 100 do not differ significantly from a traditional field effecttransistor. FinFET 100 includes a semiconductor substrate 102, local STIregion 104, a fin 106, and a gate 114 having a gate oxide layer (notshown) between the gate and the fin, configured and arranged as shown.Fin 106 includes a source region 108, a drain region 110 and a channelregion 112, wherein gate 114 extends over the top and sides of channelregion 112. For ease of illustration, a single fin is shown in FIG. 1.In practice, FinFET devices are fabricated having multiple fins formedon local STI region 104 and substrate 102. Substrate 102 may be silicon,and local STI region 104 may be an oxide (e.g., SiO₂). Fin 106 may besilicon. Gate 114 controls the source to drain current flow (labeledELECTRICITY FLOW in FIG. 1). In contrast to a planar MOSFET, however,source 108, drain 110 and channel 112 are built as a three-dimensionalbar on top of local STI region 104 and semiconductor substrate 102. Thethree-dimensional bar is the aforementioned “fin 106,” which serves asthe body of the device. The gate electrode is then wrapped over the topand sides of the fin, and the portion of the fin that is under the gateelectrode functions as the channel. The source and drain regions are theportions of the fin on either side of the channel that are not under thegate electrode. The source and drain regions may be suitably doped toproduce the desired FET polarity, as is known in the art. The dimensionsof the fin establish the effective channel length for the transistor.

Transistors have been made with silicon dioxide gate dielectrics andpoly-silicon gate conductors for decades. However, as transistors havedecreased in size, gate dielectric thickness has scaled below 2nanometers, which increases tunneling leakage currents and powerconsumption and reduces device reliability. Replacing the silicondioxide gate dielectric with a high-k material having a high dielectricconstant (k) in comparison to silicon dioxide allows increases gatecapacitance without the associated leakage effects. Suitable high-kmaterials include hafnium silicate, zirconium silicate, hafnium dioxideand zirconium dioxide, typically deposited using atomic layerdeposition.

Replacing the silicon dioxide gate dielectric with another material addscomplexity to the fabrication process. For example, implementing thegate dielectric based on high-k oxides of hafnium requires thepoly-silicon gate material to be replaced with a metal that interfacesbetter with the high-k dielectric. Accordingly, the poly-silicon gatemust be etched out and replaced with metal. The metal-gate may be formedbefore or after the source and drain regions. Forming the metal gatelast (i.e., after formation of the source and drain regions) is knowngenerally as a replacement metal gate (RMG) process flow.

Known process flows for the metal gate formation involves independentlyoptimized complex stacks of thin work-function metals topped by a bulkconductor layer. Additionally, a typical fabrication process flowincludes multiple annealing operations, including, for example, a high-kpost-deposition anneal (PDA), a high temperature anneal applied to thehigh-k dielectric to improve reliability, and a high temperature sourcedrain anneal applied to the doped source and drain regions to activatethese regions.

SUMMARY

Embodiments are directed to a method of forming portions of a fin-typefield effect transistor (FinFET). The method includes forming at leastone fin, and forming a dielectric layer over at least a portion of theat least one fin. The method further includes forming a work-functionlayer over at least a portion of the dielectric layer. The methodfurther includes forming a source region or a drain region adjacent theat least one fin, and performing an anneal operation, wherein the annealoperation anneals the dielectric layer and either the source region orthe drain region, and wherein the work function layer provides aprotection function to the at least a portion of the dielectric layerduring the anneal operation.

Embodiments are further directed to a FinFET device having at least onefin, a dielectric layer over at least a portion of the at least one fin,and a source region or a drain region adjacent the at least one fin,wherein, during a fabrication of the device, one anneal operationannealed the dielectric layer and the source region or the drain region.

Additional features and advantages are realized through techniquesdescribed herein. Other embodiments and aspects are described in detailherein. For a better understanding, refer to the description and to thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as embodiments is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features and advantages ofthe embodiments are apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings in which:

FIG. 1A depicts a three-dimensional view of an exemplary configurationof a known FinFET device;

FIG. 1B depicts a cross sectional view of a known final gate structure;

FIG. 1C depicts a cross sectional view of another known final gatestructure;

FIG. 2 depicts a semiconductor substrate, a bulk semiconductor materialand a hard mask layer after an initial fabrication stage according toone or more embodiments;

FIG. 3 depicts a cross sectional view of a semiconductor device after anintermediate fabrication stage according to one or more embodiments;

FIG. 4 depicts a cross sectional view of a semiconductor device after anintermediate fabrication stage according to one or more embodiments;

FIG. 5 depicts a cross sectional view of a semiconductor device after anintermediate fabrication stage according to one or more embodiments;

FIG. 6 depicts a cross sectional view of a semiconductor device after anintermediate fabrication stage according to one or more embodiments;

FIG. 7 depicts a cross sectional view of a semiconductor device after anintermediate fabrication stage according to one or more embodiments;

FIG. 8 depicts a cross sectional view of a semiconductor device after anintermediate fabrication stage according to one or more embodiments;

FIG. 9 depicts a cross sectional view of a semiconductor device after anintermediate fabrication stage according to one or more embodiments;

FIG. 10 depicts a cross sectional view of a semiconductor device afteran intermediate fabrication stage according to one or more embodiments;

FIG. 11 depicts a cross sectional view of a semiconductor device afteran intermediate fabrication stage according to one or more embodiments;

FIG. 12 depicts a cross sectional view of a semiconductor device afteran intermediate fabrication stage according to one or more embodiments;

FIG. 13A depicts a cross sectional view of a final gate structureaccording to one or more embodiments;

FIG. 13B depicts a cross sectional view of a final gate structureaccording to one or more embodiments; and

FIG. 14 is a flow diagram illustrating a methodology according to one ormore embodiments.

DETAILED DESCRIPTION

It is understood in advance that although this disclosure includes adetailed description of an exemplary FinFET configuration,implementation of the teachings recited herein are not limited to theparticular FinFET structure disclosed herein. Rather, embodiments of thepresent disclosure are capable of being implemented in conjunction withany other type of fin-based transistor device now known or laterdeveloped.

For the sake of brevity, conventional techniques related to FinFETsemiconductor device fabrication may not be described in detail herein.Moreover, the various tasks and process steps described herein may beincorporated into a more comprehensive procedure or process havingadditional steps or functionality not descried in detail herein. Inparticular, various steps in the manufacture of semiconductor basedtransistors are well known and so, in the interest of brevity, manyconventional steps will only be mentioned briefly herein or will beomitted entirely without providing the well-known process details.

As previously noted herein, replacing the silicon dioxide gatedielectric with another material adds complexity to the manufacturingprocess. For example, implementing the gate dielectric based on high-koxides of hafnium requires the poly-silicon gate material to be replacedwith a metal that interfaces better with the high-k dielectric.Accordingly, the poly-silicon gate must be etched out and replaced withmetal. The metal-gate may be formed before or after the source and drainregions. Forming the metal gate last (i.e., after formation of thesource and drain regions) is known generally as a replacement metal gate(RMG) process flow.

FIGS. 1B and 1C depict cross sectional views of known final (i.e., postfabrication) configurations for gate 114 shown in FIG. 1A. FIG. 1Bdepicts an n-type FET gate 114A configuration, and FIG. 1B depicts ap-type FET gate 114B configuration. In either configuration, the finalgate includes independently optimized complex stacks of thinwork-function metals of tungsten (W), titanium nitride (TiN) andtitanium carbide (TiC), along with high-k dielectric layers 122, 122A.Known process flows for fabricating gate configurations 114A, 114B formhigh-k dielectric layers 122, 122A later in the fabrication process,typically after the POC (poly-silicon open CMP) process and before thegate last, RMG process. The RMG process applied to the gateconfigurations 114A, 114B shown in FIGS. 1B and 1C includes theformation of a dummy gate structure (not shown in FIGS. 1B and 1C) usedto self-align the source and drain implant and anneals. The dummy gatematerials are then stripped out and replaced with the high-k dielectricand metal gate materials.

A typical fabrication process flow used to form gate configurations114A, 114B includes multiple anneal operations, including a high-k PDA,a high temperature source drain “activation” anneal applied to the dopedsource and drain regions to activate these regions, and a subsequenthigh temperature “reliability” anneal operation applied to high-kdielectric layers 122, 122A to improve the reliability of these layers.Additionally, when formed after the POC process, high-k dielectriclayers 122, 122A extend horizontally substantially along elongatedsurfaces of sidewalls 130, 130A of gates 114A, 114B, which reduces thetotal volume of the metal gate materials (e.g., W, TiN, TiC, etc.) thatcan be formed in the gate region between sidewalls 130, 130A.

Turning now to an overview of the present disclosure, one or moreembodiments provide a fabrication process flow and resulting devicestructure of a fin-type field effect transistor (FinFET) that uses anovel “high-k p-type work function metal first” fabrication process thatimproves the efficiency of source/drain activation annealing andreliability annealing, and also improves the total width (e.g., width1324 shown in FIGS. 13A and 13B) available for formation of the metalgate materials (e.g., W, TiN, etc.) in the gate region. Morespecifically, instead of forming a high-k dielectric layer later in thefabrication process flow, one or more disclosed embodiments form thehigh-k dielectric layer “first,” which for a FinFET device means thatthe high-k dielectric layer is formed before formation of the sourcedrain regions. Additionally, instead of forming all work-function metalgate layers later in the process flow (e.g., during the RMG process) awork-function metal layer (e.g., a cap TiN layer of from about 10 toabout 50 Angstroms (Å) in thickness) is deposited over the high-kdielectric layer. Because the high-k dielectric layer is already inplace when the source drain regions are formed, the high temperatureannealing of both the high-k dielectric layer and the source drainregions can performed as a single annealing operation. Additionally,because a work-function metal layer is in place over the high-kdielectric layer when the source drain regions are formed, thework-function metal protects the high-k dielectric layer during the hightemperature annealing of both the high-k dielectric layer and the sourcedrain regions. Further, forming the high-k dielectric layer “first”allows the area occupied by the high-k dielectric layer to be controlledsuch that the high-k dielectric material does not extend along thesidewalls of the gate structure, which leave more volume between thesidewalls for the formation of the final metal gate structure.Increasing the available volume between the sidewalls for forming thegate structure results in a lower resistance of the resulting gatestructure.

A fabrication methodology for forming various stages of a FinFETsemiconductor device in accordance with one or more embodiments of thepresent disclosure will now be described with reference to FIGS. 2-12.Referring now to FIG. 2, an initial structure is formed havingsemiconductor substrate 202, a bulk semiconductor material 204 and ahard mask layer 206, configured and arranged as shown. It is noted thatbulk semiconductor material 204 and semiconductor substrate 202 may besubstantially the same material. Hard mask layer 206 may be a siliconnitride material (e.g., Si₃N₄). In FIG. 3, a patterned resist 302 isadded over hard mask layer 206 to pattern and form fins 402 (shown inFIG. 4) from bulk semiconductor 204. Fins 402 may be formed by applyingan anisotropic etch process, which results in the structure shown inFIG. 4. Because there is no stop layer on semiconductor substrate 202,the etch process is time based. Bulk semiconductor 204 may also beimplemented as a silicon-on-insulator (SOI) structure, wherein a buriedoxide (BOX) layer of the SOI would act as an etch stop. In FIG. 5, alocal oxide (e.g., SiO₂) is deposited between fins 402 and oversubstrate 202. For ease of illustration, only one fin is labeled with areference number. As shown in FIGS. 6 and 7, the local oxide is polishedand recessed back to form local STI regions 606, and to expose upperportions of fins 402. Again, for ease of illustration, only one localSTI region is labeled with a reference number.

In FIG. 8, an interfacial/high-k dielectric layer 804 and a TiN layer802 are deposited over fins 402 and STI 606. For p-type configurationsof the present disclosure (e.g., as shown in FIG. 13B and described ingreater detail herein below) TiN layer 802 will form part of thework-function layers of the ultimate metal gate structure. TiN layer 802and a poly-silicon gate/PC layer 902 (shown in FIG. 9A) provideprotection for interfacial/high-k dielectric layer 804 and preventre-growth of interfacial/high-k dielectric layer 804 during subsequenthigh temperature anneal operations. Interfacial/high-k layer 804 isdeposited, followed by a nitridation and a PDA at approximately 700degrees Celsius for approximately 30 seconds, followed by deposition ofa cap TiN layer 802 of from about 10 to about 50 Angstroms (Å) inthickness. In accordance with one or more embodiments,interfacial/high-k layer 804 and TiN layer 802 are formed after finformation and before the PC module (i.e., gate module) formation, thespacer and epitaxial source/drain formation, and the POC process. Thisis in contrast to known fabrication methodologies, wherein theinterfacial/high-k layer is formed after the PC module formation, thespacer and epitaxial source/drain formation, and the POC process, andwherein the work-function layers are all formed as part of the RMGprocess.

As shown in FIG. 9, poly-silicon gate/PC layers 902 and nitrided hardmasks 904 are deposited over TiN layers 802. FIG. 10 depicts a crosssectional view of the FinFET device after a subsequent fabricationstage, wherein the device has been rotated by 90 degrees such that fins402 extend through and between poly-silicon gate/PC layers 902. FIG. 10depicts the FinFET device after a fabrication stage wherein fins 402,interfacial/high-k layers 804 and TiN layers 802 have been recessed inthe areas not covered by poly-silicon gate/PC layers 902, and the onlyremaining portions of fins 402, interfacial/high-k layers 804 and TiNlayers 802 are the portions of fins 402 that form the channel regions,along with the portions of interfacial/high-k layers 804 and TiN layers802 that cover the fin channel regions. The fin channel regions,interfacial/high-k layers 804 and TiN layers 802 are surrounded bypoly-silicon gate/PC layers 902 and are not visible in FIG. 10. Offsetspacers 1002 are formed along the sidewalls of poly-silicon gate/PClayers 902, as shown. Offset spacers 1002 may be formed using a spacerpull down formation process. Offset spacers 1002 may also be formedusing a sidewall image transfer (SIT) spacer formation process, whichincludes spacer material deposition followed by directional RIE of thedeposited spacer material.

As shown in FIG. 11, raised source drain (RSD) regions 1102 aredeposited using an epitaxial layer deposition process. RSD regions 1102may be suitably doped to produce the desired FET polarity. A hightemperature anneal (e.g., from about 1000 to about 1025 degrees Celsius)is now applied. The high temperature anneal may be a spike anneallasting less than about 1 second. In accordance with one or moreembodiments of the present disclosure, because the interfacial/high-kdielectric layers 804 (shown in FIGS. 8 and 9) are already in place whenRSD regions 1102 are formed, the high temperature annealing of both theinterfacial/high-k dielectric layers 804 and RSD regions 1102 canperformed as a single annealing operation. Additionally, because TiNlayers 802, which will subsequently function as work-function metallayer, are in place over interfacial/high-k layers 804 when RSD regions1102 are formed, TiN layers 802 protect interfacial/high-k layers 804during the high temperature annealing of both interfacial/high-kdielectric layers 804 and RSD regions 1102. Further, forminginterfacial/high-k dielectric layers 804 and TiN layers 802 “first”allows the area occupied by interfacial/high-k dielectric layer 804 tobe controlled such that interfacial/high-k dielectric layers 804 do notextend along the offset spacers 1002 of the gate structure, which leavesmore volume for the formation of the final metal gate structure.Increasing the available volume for forming the metal gate structureresults in a lower resistance of the resulting gate structure.

FIG. 12 depicts a stage of the fabrication process flow after the polyopen CMP (POC) process but before the metal gate deposition. In agate-last fabrication process, poly-silicon gate/PC layers 902 comprisea dummy gate structure that may be removed and replaced with a metalgate (e.g., shown in FIGS. 13A and 13B). Poly-silicon gate/PC layers 902can be removed by an etching process, e.g., RIE or chemical oxideremoval (COR), to form a trench. A gate metal (not shown in FIG. 12) cansubsequently be deposited within the trench. More specifically, a metalliner, e.g., a work-function metal, and a gate metal can then bedeposited on the high-k dielectric material to complete the gateformation. In one or more embodiments, the metal liner can be, forexample, TiN or TaN, and the gate metal can be aluminum or tungsten. Asilicon dielectric 1204 is deposited over RSD regions 1102.

FIGS. 13A and 13B depict cross sectional views of final (i.e., postfabrication) configurations of gates 1320, 1320A that would result fromimplementation of one or more embodiments of the high-k p-typework-function metal first fabrication process flow of the presentdisclosure. FIG. 13A depicts an n-type FET gate 1320 configuration, andFIG. 13B depicts a p-type FET gate 1320A configuration. In eitherconfiguration, the final gate includes independently optimized complexstacks of thin work-function metals of tungsten (W), titanium nitride(TiN) and titanium carbide (TiC), along with high-k dielectric layers1322, 1322A. During fabrication of gates 1320, 1320A, instead of formingthe high-k dielectric layer later in the fabrication process flow, oneor more disclosed embodiments form the high-k dielectric layer and a TiNwork-function layer “first,” which for a FinFET device means that thehigh-k dielectric layers 1322, 1322A and TiN work-function layer (shownfor the pFET gate configuration 1320A in FIG. 13B) are formed beforeformation of the source drain regions. For the nFET gate configuration1324 shown in FIG. 13A, the TiN layer has been etched away in the finalgate configuration. Because the high-k dielectric layers 1322, 1322A andTiN work-function layer are already in place when the source drainregions are formed, the high temperature annealing operation of both thehigh-k dielectric layers 1322, 1322A and the source drain regions can beperformed as a single annealing operation. Additionally, because the TiNlayer, which in the final gate configuration functions as part of thework-function metal layers, is in place over high-k layers 1322, 1322Awhen RSD regions 1102 (shown in FIGS. 11 and 12) are formed, TiN layerprotects high-k layers 1322, 1322A during the high temperature annealingof both high-k dielectric layer 1322, 1322A and RSD regions 1102.Additionally, forming the high-k dielectric layer and TiN work-functionlayer “first” allows the area or volume occupied by the high-kdielectric layers 1322, 1322A to be controlled such that the high-kdielectric material does not extend substantially along elongatedsurfaces of sidewalls 1330, 1330A of the gate structure, which leavesmore volume for the formation of the final metal gate structure.Increasing the available volume for forming the gate structure resultsin a lower resistance of the resulting gate structure. The elongatedsurfaces of sidewalls 1330, 1330A extend for a dimension that issignificantly more than a width dimension of sidewalls 1330, 1330A.

FIG. 13B includes an additional legend showing an x-y axis of thecross-sectional view of gate configurations 1320, 1320A shown in FIGS.13A and 13B, which may be used to further illustrate that high-kdielectric layers 1322, 1322A do not extend substantially along anelongated surface of sidewalls 1330, 1330A. This legend also applies togate configurations 114A, 114B shown in FIGS. 1B and 1C. As illustrated,high-k dielectric layers 1322, 1322A extend substantially along an xdirection of gate configurations 1320, 1320A but do not extendsubstantially along a y direction of gate configurations 1320, 1320A. Incontrast, the prior art gate configurations 114A, 114B include high-kdielectric layers 122, 122A that extend substantially along an xdirection of gate configurations 114A, 114B and substantially along a ydirection of gate configurations 114A, 114B.

FIG. 14 is a flow diagram illustrating a methodology 1400 according toone or more embodiments. Although the operations of methodology 1400 areillustrated in a particular order, it will be understood by persons ofordinary skill in the relevant art that the order of the illustratedoperations may be changed without departing from the teachings of thepresent disclosure. In addition, it will be understood by persons ofordinary skill in the relevant art that one or more of the illustratedoperations may be omitted, and/or operations not shown (e.g., routineintermediary operations) may be incorporated, without departing from theteachings of the present disclosure.

As shown in FIG. 14, methodology 1400 begins at block 1402 by forming atleast one fin. Block 1404 forms a dielectric layer (e.g., a high-kdielectric) over at least a portion of the at least one fin. Thedielectric layer may include an interfacial layer. Block 1404 mayinclude a post deposition anneal operation, which may be performed atapproximately 700 degrees Celsius for approximately 30 seconds. Block1405 deposits a work-function metal layer (e.g., a cap TiN layer of fromabout 10 to about 50 Angstroms (Å) in thickness) over the high-kdielectric layer. Block 1406 forms a dummy gate/PC over the dielectriclayer, and block 1408 forms spacer sidewalls along the dummy gate/PC.Block 1410 forms the source/drain regions and performs an annealoperation. The anneal operation is a high temperature anneal, whichincludes a temperature above about 1000 Celsius. The anneal operationmay be a spike anneal operation that lasts less than approximately 1second. In accordance with one or more embodiments of the presentdisclosure, because the high-k dielectric layer is already in place whenthe source/drain regions are formed, the high temperature annealoperation anneals both the high-k dielectric layer and the source/drainregions in a single, spike annealing operation. Additionally, becausethe work-function metal layers are is in place over the dielectric layerwhen the source/drain regions are formed, the work-function metal layerprotects the dielectric layer during the high temperature annealing ofboth the dielectric layer and the source/drain regions. Further, forminghigh-k dielectric layer and at least one of the work-function layers“first” allows the area occupied by high-k dielectric layer 804 to becontrolled such that the high-k dielectric layer does not extendsubstantially along an elongated surface of the spacers that define thegate structure, wherein more volume is available for the formation ofthe final metal gate structure. Increasing the available volume forforming the gate structure results in a lower resistance of theresulting gate structure. Block 1412 performs a POC process to removethe poly-silicon dummy gate/PC, and block 1414 performs a known RMGprocess that replaces the poly-silicon dummy gate/PC with a metal gate.

In an alternative embodiment, the high temperature anneals are combinedinto a single anneal and performed at some point in the process afterthe high-k dielectric layer has been deposited and the source drainregions have been formed, and the other fabrication steps shown in FIG.14 may be performed in any order.

Thus, it can be seen from the forgoing detailed description andaccompanying illustrations that embodiments of the present disclosureprovide structures and methodologies for forming a high-k dielectricregion of a FinFET device having improved reliability annealing andsource drain activation annealing. As described above, one or moreembodiments provide a fabrication process flow and resulting devicestructure of a fin-type field effect transistor (FinFET) that uses anovel “high-k p-type work-function first” fabrication process thatimproves the efficiency of source/drain activation annealing andreliability annealing, and also increases the total volume available forformation of the replacement metal gate in the gate region. Morespecifically, instead of forming a high-k dielectric layer and at leastone of the work-function layers later in the fabrication process flow,one or more disclosed embodiments form the high-k dielectric layer andat least one of the work-function layers “first,” which for a FinFETdevice means that the high-k dielectric layer and at least one of thework-function layers are formed before formation of the source drainregions. Because the high-k dielectric layer and at least one of thework-function layers are already in place when the source drain regionsare formed, the high temperature annealing of both the high-k dielectriclayer and the source drain regions can performed as a single annealingoperation. Additionally, forming the high-k dielectric layer “first”allows the area occupied by the high-k dielectric layer to be controlledsuch that the high-k dielectric material does not extend along thesidewalls of the gate structure, which leave more volume for theformation of the final metal gate structure. Increasing the availablevolume for forming the gate structure results in a lower resistance ofthe resulting gate structure.

The method as described above is used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

The descriptions of the various embodiments of the present disclosurehave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein. As used herein, the singular forms “a”, “an” and “the”are intended to include the plural forms as well, unless the contextclearly indicates otherwise. It will be further understood that theterms “comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,element components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A method of forming portions of a fin-type fieldeffect transistor (FinFET), the method comprising: forming at least onefin; forming a dielectric layer over at least a portion of the at leastone fin; forming a work function layer over at least a portion of thedielectric layer; forming a source region or a drain region adjacent theat least one fin; and performing an anneal operation; wherein the annealoperation anneals the dielectric layer and either the source region orthe drain region; wherein, prior to the anneal operation, the dielectriclayer and either the source region or the drain region have notundergone a previous anneal operation; wherein the work function layerprovides a protection function to the at least a portion of thedielectric layer during the anneal operation.
 2. The method of claim 1,wherein the dielectric layer comprises an oxide of hafnium.
 3. Themethod of claim 1, wherein the dielectric layer includes an interfaciallayer.
 4. The method of claim 1, wherein the anneal operation comprisesa temperature above about 1000 degrees Celsius.
 5. The method of claim 1further comprising forming, subsequent to the formation of thedielectric layer, a dummy gate over the dielectric layer.
 6. The methodof claim 5 further comprising forming at least one sidewall on the dummygate.
 7. The method of claim 6, wherein the dielectric layer does notextend along an elongated surface of the at least one sidewall.
 8. Themethod of claim 7 further comprising removing the dummy gate.
 9. Themethod of claim 8 further comprising forming a replacement gate in aspace that was occupied by the dummy gate.
 10. The method of claim 9,wherein: the replacement gate comprises a metal; and the metal comprisesat least one of the following: tungsten; titanium nitride; and titaniumcarbide.
 11. A method of forming portions of a fin-type field effecttransistor (FinFET), the method comprising: forming at least one fin;forming a dielectric layer over at least a portion of the at least onefin; forming, subsequent to the formation of the dielectric layer, adummy gate over the dielectric layer; forming at least one sidewall onthe dummy gate; forming a work function layer over at least a portion ofthe dielectric layer; and forming a source region or a drain regionadjacent the at least one fin; wherein the dielectric layer does notextend along an elongated surface of the at least one sidewall.
 12. Themethod of claim 11 further comprising: performing an anneal operation;wherein the anneal operation anneals the dielectric layer and either thesource region or the drain region; wherein the work function layerprovides a protection function to the at least a portion of thedielectric layer during the anneal operation.
 13. The method of claim12, wherein, prior to the anneal operation, the dielectric layer andeither the source region or the drain region have not undergone aprevious anneal operation.
 14. The method of claim 11, wherein thedielectric layer comprises an oxide of hafnium.
 15. The method of claim11, wherein the dielectric layer includes an interfacial layer.
 16. Themethod of claim 13, wherein the anneal operation comprises a temperatureabove about 1000 degrees Celsius.
 17. The method of claim 11 furthercomprising removing the dummy gate.
 18. The method of claim 17 furthercomprising forming a replacement gate in a space that was occupied bythe dummy gate.
 19. The method of claim 18, wherein: the replacementgate comprises a metal; and the metal comprises at least one of thefollowing: tungsten; titanium nitride; and titanium carbide.